How to measure your waist, hips and chest the same way every time

Waist: choose one landmark and keep it

The two manuals put the waist tape in different places.

• WHO STEPS: the midpoint between the lower margin of the last palpable rib and the top of the iliac crest (the hip bone). Find both by touch, then put the tape at the halfway point.
• CDC NHANES: just above the uppermost side edge of the right iliac crest, at the level of a mark made where that edge meets the midaxillary line (the line running down your side from the armpit). The tape goes around at the level of that mark.

Because the two methods measure at different places, one person can get different numbers from each. Pick one method, write its name in your notes (for example "WHO midpoint"), and don't compare a reading taken one way with a reading taken the other.

Then take the reading the same way every time:

1. Stand with your feet together and your weight even on both feet. WHO has the arms relaxed at your sides. NHANES has them crossed, with each hand on the opposite shoulder, to keep them out of the way. Choose one and keep it.
2. Wrap the tape level. It should be as parallel to the floor as possible, front and back. Check it in a mirror. Both manuals say snug, but not tight enough to press into the skin.
3. Breathe normally for a few breaths, then read the tape at the end of a normal breath out. Both manuals use this point. That means not breathing in deeply and not pulling your stomach in.
4. Read it straight on. NHANES tells staff to keep the zero end of the tape below the number being read, and to read with their line of sight directly in front of the value, because reading from an angle shifts the number.
5. Read to the nearest 0.1 cm. Both manuals use that precision. If you use inches, read to the smallest mark on your tape and do the same every time.

Measure over bare skin or light clothing. WHO says the waist measurement must not be taken over thick or bulky clothing.

Chest and thigh

Neither the WHO STEPS section nor the NHANES manual describes a chest or thigh circumference. (NHANES does measure upper-leg length, but that's a distance from the groin crease to the kneecap, not a circumference.) There's no WHO or CDC method to cite for these two.

What you can do is apply the principles the two manuals share:

• Choose a landmark you can find by touch or in a mirror, and describe it in words in your notes so you can find it again.
• Keep the tape level and snug, without pressing into the skin.
• Read at the end of a normal breath out, standing the same way each time.
• Use the same side of the body and the same tape.

Your own landmark is consistent with itself, but it's not a standard, so don't compare it with anyone else's number.

How Peptimes helps

Peptimes records body measurements from the "Your measurements" card in Body Profile: waist, hips, chest, upper arm, thigh and body fat percentage. Lengths are in inches or centimeters, following how height is shown in Body Profile, and body fat is in %. The "Log measurements" sheet starts with a date, any day up to today, so you can add a reading you took earlier. Each measurement is optional: enter the ones you measured and leave the rest empty. There's one entry per day, so logging a day again replaces it. You can tap a measurement to see its history. Peptimes stores the date and the numbers, so keep your method notes (landmark, tape, clothing) in your own notes.

Your health records are stored on your iPhone. Peptimes doesn't keep a copy of them on its servers, and your records may not come across to a new iPhone, so export a copy first. You can export your records as CSV or JSON to keep or to bring to an appointment. Peptimes records the numbers you enter and doesn't interpret them. For a weight record kept to the same standard, see how to weigh yourself consistently.